Results 1 - 10 of 4398
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[en] Lead-free (1-x)(Bi0.5Na0.5)TiO3-xSrTiO3 (abbreviated as BNT-100xST, x = 0.19–0.27) piezoceramics were synthesized via the traditional solid-state process. The micromorphology, phase structure, strain response and fatigue behavior were studied in detail. For all the composition range, the ceramics are pure perovskite structures. And the tetragonal phase gradually changes into pseudocubic phase. The ferroelectric order was destroyed with the increase of ST concentration. Strains up to 0.289% for BNT-23ST can be achieved at the driving fields (45 kV cm−1) with a high corresponding normalized strain d 33 * (S max/E max) of 642 pm V−1. Furthermore, the BNT-23ST ceramics exhibit an excellent fatigue resistance, and the unipolar strain value decreased by only 8.24% after 107 cycles. (paper)
[en] The structure and phase composition of SrTiO3 films produced by HF magnetron scattering on monocrystal Si (111) substrate have been studied by the methods of transmission electron microscopy and X-ray diffractometry. The influence of the impurity phases concentration on the value of dielectric permittivity of the films has been studied
[en] In the present study, a truncated pyramid structure was adopted to analyze the effect of the configuration of structures on the flexoelectric effect. In order to use the flexoelectric effect as sensing mechanism, the flexoelectric material, barium strontium titanate (Ba0.65Sr0.35TiO3 - BST) ceramic, which has been known to have the highest flexoelectricity at room temperature until now, was used for the analysis. The flexoelectric output is influenced by not only the dimensions of the structure but also the edge processing. Depending on the shape and amount of edge style, the difference in charge output between the designed and actual fabricated can exist up to 51 %. The results can offer a guide for designing flexoelectric sensors in micro and nano scales.
[en] Density functional theory calculations of twin-domain walls in strontium titanate are presented. The two possible domain walls are characterized. The domain wall type is set by the relative phase of the octahedral rotations in the body-centered-tetragonal SrTiO3 on either side of the domain wall. The width of the domain walls is estimated to be approximately 3 nm. (paper)
[en] We present ab initio calculations of the longitudinal flexoelectricity for BaTiO3 and SrTiO3 using a direct approach. The calculated value for SrTiO3 agrees with recently reported measurements. For BaTiO3, however, the theoretical values are smaller than the measured ones; possible reasons for the discrepancy are discussed. (fast track communication)
[en] We investigate strontium titanate as a model waste form for 90Sr. Implantation with O+ and Zr+ ions, followed by annealing at 1423 K, was performed to simulate 90Sr to 90Zr decays. At low Zr concentrations, we observe formation of a ZrO-Sr superlattice structure. Ab initio calculations indicate that this atomic configuration is energetically favorable. At higher Zr concentrations, we observe precipitates of ZrO2 with a coherently strained interface, or a monolayer of disordered interfacial structure. Potential candidacy of 90SrTiO3 as a waste form for permanent disposal of 90Sr is discussed.
[en] The structural properties of symmetrical low-angle  (01l) tilt grain boundaries in the perovskite oxide SrTiO_3 were investigated by empirical pair potentials and energy minimisation techniques. Thirteen interfaces with misorientation angles varying between θ = 3° and θ = 22.6° were studied in both stoichiometric and oxygen deficient forms. Examination of the relaxed simulation cells indicated that all the studied grain boundaries consisted of some combination of two different types of dislocation core. The structures of the two types of dislocation core remain unchanged at low misorientation angles but become increasingly distorted at the highest angles examined. Simple rules were derived to predict the type, arrangement and alignment of the dislocations at a given interface.
[en] A nearly perfect dual-band deep sub-wavelength scale and temperature-controlled terahertz absorber is theoretically investigated. The absorber is composed of a periodic metal-dielectric stack array placed on a metallic substrate. Simulation results show that there are two distinct absorption peaks located at frequencies of about 0.140 THz and 0.192 THz in the spectra line under room temperature T = 300 K, and their maximum absorption rates are respectively 99.133% and 98.251%. It is also found that the period of the unit cell is less than 8.97% of the minimum resonant wavelength, which means the deep sub-wavelength absorber structure. Furthermore, it is shown that the proposed absorber is polarization-insensitive, and has good tolerance to the incident angle for both TE and TM wave, i.e., it is pantoscopic for the incident light. Meanwhile, when the temperature changes from 200 K to 400 K, the absorption of the two peaks did not change significantly within the considered frequency range, but the resonant frequency of the two absorption peaks will have a clear blueshift. The effect of structural parameters on the absorbing performance have also been discussed. This work provides a new idea for the design of frequency-agile deep sub-wavelength scale perfect THz absorbers, and the design scheme may be easily extended to the near ultraviolet, optical, infrared, terahertz and millimeter-wave regions. (paper)
[en] Sr2TiO4:Cr complexes are found to possess photochromism. After the photochromism, the catalytic performance of the complexes for H2 generation increases markedly. In fact, it was found that the performance increased more than 20 times compared to the original Sr2TiO4: 10 mol % Cr complex. These results suggest that it is worthwhile searching and optimizing visible-light-sensitive photocatalysts by investigating possible photochromism.